Ultraviolet irradiation of [PPh4][closo-1-CB8H9] with [Re-2(CO)(10)] in THF (tetrahydrofuran) at ambient temperature affords the dirhenacarborane anion [6,10-{Re(CO)(4)}-10-(mu-H)-6,6,6-(CO)(3)-closo-6,1-ReCB8H8](-), isolated as its [PPh4](+) salt (1). Further irradiation of 1 yields a second isomeric anion [6,10-{Re(CO)(4)}-6-(mu-H)-10,10,10-(CO)3-closo-10,1-ReCB8H8](-) that was characterized as a [N(PPh3)(2)](+) salt (2). Reaction of 1 with NOBF4 produces the neutral dirhenacarborane compound [8,10-{Re(CO)(4)}-8,10-(mu-H)(2)-6,6-(CO)(2)-6-NO-closo-6,1 -ReCB8H7] (3). Compounds 1-3 all consist of a central {closo-ReCB8} cluster with a second rhenium center which is exo-polyhedral. Attempts to substitute the carbonyl ligands of 3 with other donor ligands such as phosphines, isocyanides, or alkynes resulted in loss of the exo-polyhedral rhenium moiety and formation of a monorheniurn anion, [6,6-(CO)(2)-6-NO-closo-6,1-ReCB8H9](-), isolated as its [N(PPh3)(2)](+) salt (4). The heterometallic dimetallacarborane species, [6,7,(CO)(2)-Cu(pph(3))}-7,10 -(mu-H)(2)-6,6-(CO)(2)-6-NO-closo-6,1 -ReCB8H7] (5) and [6,7-{Au(PPh3)}-7-(mu-H)-6,6-(CO)(2)-6-NO-closo-6,1-ReCB8H8] (6) were formed from reactions of 4 with {Cu(PPh3)}+ and {Au(PPh3)}(+), respectively. Similarly, reaction of 4 with {lr(CO)(PPh3)(2)}(+) afforded two products, [6,10-{lr(mu-PPh2)(Ph)(CO)(PPh3)}-10-(mu-H)-6-CO-6-NO-closo-6,1-ReCB8H8] (7) and [6,9,10-{lr(mu-PPh2)(H)(PPh3)}-9-(mu-H)-6-CO-6-NO-10-Ph-closo-6,1-ReCB8H 8] (8). The solid-state structures of compounds 1-8 were all unequivocally established by single-crystal X-ray diffraction experiments.